Magnetron sputtering systems, such as suggested in U.S. Pat. No. 4,166,018, have used rotatable arrays of permanent magnets arranged in polar pairs in generally heart-shaped configurations, as suggested by U.S. Pat. Nos. 4,872,964 and 4,995,958, to form a generally heart-shaped magnetic path proximate to a target that is eroded by sputtering. Uniform erosion of the target has been emphasized, partly for target erosion purposes and partly to ensure that a coating is applied uniformly on a surface of a substrate. Prior art magnetrons of this type have generally settled on heart-shaped configurations for the permanent magnet arrays and the resulting magnetic paths, as an optimum configuration to enhance uniformity of the sputtering process.
We have discovered, however, that conventionally shaped magnetrons produce substrate coatings whose uniformity is less than optimum. In seeking to remedy this, we have discovered that an improved magnetron shape, departing from the conventional heart shape, produces a substrate coating that is substantially more uniform.